Abstract

Abstract

A preliminary second-order soil survey (1:15840) of Squaw Butte Range Exp. Stn., Oregon, identified a single shallow upland soil that supported six contrasting sagebrush communities. Six delineations of this soil, each associated with different vegetation, were sampled intensively to objectively determine if soil properties and classification differed between delineations. Plant communities represented six different sagebrush (Artemisia) habitat types: A. longiloba/Agropyron spicatum, A. longiloba/(fescue) Festuca idahoensis, A. arbuscula/F. idahoensis, A. tridentata ssp. wyomingensis/A. spicatum, (F. idahoensis), and A. t. ssp. vaseyana/F. idahoensis-A. spicatum. Morphological properties of profile samples were statistically compared by defining aggregate horizons (tiers) that were common to all profiles. Stepwise discriminant analysis selected elevation, aspect, presence of E and BA horizons, clay content of the Bt horizon, and sand content of surface strata as those which best distinguished between plant communities. Evidence suggests that series separations are justified based on family and class distinctions of higher categories or differences in range of soil properties, including variations in horizonation, volumetric rock fragment content of A and Bt horizons, and structure of BAt horizons. Phase separation criteria suggested include aspect, parent material, slope, and surface texture. Structure type of subhorizons, subhorizon position, and nutrient content are soil properties that may also provide important discrimination between soils possessing different range potentials.

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